The present invention relates to a device to reduce airflow noises on elevator cars travelling at high speed. The device is in the form of an aerodynamically favorably formed dome that is attached either on the car roof or under the car floor or in both positions.
An elevator car is part of an elevator installation, which consists essentially of the following components: an elevator hoistway with guiderails, the elevator car mentioned above with its car frame, a counterweight, the suspension ropes for car and counterweight, and a drive unit with traction sheave which drives these suspension ropes. High-speed cars are also connected on their underside to the counterweight by a compensating rope that runs over a pulley in the hoistway pit. The elevator car is elastically supported in the car frame, which hangs from the suspension ropes, is guided in the direction of travel by the guiderails acting on guiding elements, and is constructed robustly to allow for the stresses occurring in operation and when breakdowns occur.
Cars of elevator installations are usually constructed as aerodynamically unfavorable cuboid bodies with sharp edges and move in mostly narrow elevator hoistways. At travel speeds above about 4 m/s the occurrence of air eddies and flow separation cause noises that are unpleasant or even highly irritating. To reduce these noises, dome-like attachments of aerodynamically favorable shape are attached to high-speed elevator cars in one, or both, directions of travel with the objective of guiding the displaced air volume around the car body with as little eddying or separation as possible. The U.S. Pat. No. 5,220,979 discloses several solutions for attachments to elevator cars to improve airflow. All the solutions described there have the characteristics that on the same side as the entrance of the elevator car they have flat surfaces extending in the direction of the continuation of the car front wall downward, or downward and upward, and that their walls are constructed as robust plates or shaped parts.
The British patent document GB 2 280 662 also describes devices to improve the flow characteristics of elevator cars, the passenger car being built into a closed housing which is constructed in an aerodynamically favorable manner. As in the U.S. Pat. No. 5,220,979, the aerodynamically favorable housings shown in the patent document GB 2 280 662 also have on the same side as the entrance of the elevator car flat surfaces extending in the direction of the continuation of the car front wall upward or downward and the walls of these housings are constructed of robust, shaped parts.
Both the solutions mentioned have the disadvantages that the disclosed aerodynamically favorable attachments and housings are heavy and bulky components which require voluminous packing, are difficult to transport and install, and enormously increase the weight of the car to be moved by the elevator installation. Furthermore, manufacturing domes with multiaxially curved surfaces, as they are described in both documents, is very costly, particularly as the domes must be adapted to a large number of different car dimensions.